| 摘要 |
A method and apparatus for subterranean drilling and mining, particularly suited to alluvial deposits, wherein pressurised water is fed to the annular space between pipes 6 and 16, is allowed to pass out of nozzles 8 and 17, and is removed with the spoil through pipe 6. Part of the water is bled off to raise a piston 5 and associated weight 4, the water being evacuated from the cylinder in which the piston operates from time to time to give periodic impulses to outer casing 11. Air is admitted to the water which provides the water jets during mining operations to create an air bubble in the mining chamber and thereby increase the efficiency of operation of the water jets. <IMAGE> |
